1. Field
The present invention relates to the detection of tampering with electronic circuits.
2. Background Information
An electronic circuit may be subjected to tampering by third parties attempting to ascertain internal operations of the circuit. For example, the circuit may perform an encryption operation on data using a secret value known as a key. It may be difficult for third parties to ascertain the key value by simply examining the input and output signals to the circuit. By tampering with the circuit, these parties may gain insight into the value of the key employed in the encryption operation.
One form of tampering involves using chemicals or mechanical processes to strip away materials in which the circuits are encased. Such material may include “passivation material”, e.g. a form of dielectric or insulator, and may be stripped using chemicals to expose conductive elements of the circuits. Probes may then be placed on the conductive elements to measure signals produced by internal operations of the circuit. The measurements may allow a third party to ascertain information about the internal operation of the circuit.